Custom E-commerce Payment Gateway

I need a seasoned developer to build a payment gateway entirely from scratch something like checkout.com . The core engine must process real-time sales, captures, refunds, and voids while meeting strict PCI-DSS requirements and passing 3-D Secure 2.0 checks.

Connections to be established: Cybersource, Mastercard Payment Gateway Services, and several domestic bank APIs (full specs will be shared after NDA). All routing, tokenisation, and risk responses should be abstracted behind a clean REST/JSON interface so the storefront can call a single, unified endpoint regardless of the underlying acquirer.

Multi-currency support is essential; settlements will initially run in USD, EUR, and AED, with room to add more. Please architect currency tables, FX mark-ups, and reconciliation reports accordingly.

Deliverables
• Production-ready gateway code (language/framework of your choice, as long as it is well-documented and maintainable)
• Secure merchant-facing dashboard for transaction search, manual captures, and refund initiation
• Automated test suite and sandbox environment that emulates Cybersource, MPGS, and the bank endpoints
• Deployment scripts or Docker files so the stack can be spun up in staging and production with one command
• Technical documentation covering API endpoints, field validation rules, error codes, and onboarding steps

Acceptance will hinge on a live demo showing an end-to-end e-commerce purchase flowing through the new gateway, settling in at least two currencies, and being fully traceable in the dashboard and logs.